By Lisa Baertlein

LOS ANGELES Cargo volume at the Port of Los Angeles jumped from July to August after business lost during the now-finished West Coast labor talks began returning, the top executive at the nation's busiest ocean trade gateway said on Thursday.

That data comes as seaports on the U.S. West Coast are battling to regain market share lost to rivals on the East Coast and the Gulf of Mexico during the 13-month union negotiations, and as ocean cargo volumes tumble from early pandemic highs.

In August, the Port of Los Angeles handled 828,016 20-foot equivalent units, a measurement standard for ocean cargo. That was up almost 3% from the year earlier and 21% above July, when volume swooned due to worried shippers rerouting goods.

As West Coast ports labor talks dragged on, affected operators lost market share to other U.S. rivals. Port employers and the longshore union reached a tentative contract agreement covering 22,000 dockworkers on June 15 and employees ratified the deal on Aug. 31.

In the final stretch of those talks, "folks made some very fast decisions to move cargo away from the West Coast" to avoid having containers stranded by a work stoppage, Port of Los Angeles Executive Director Gene Seroka said. That sent volume down sharply in July but business quickly resumed after the handshake agreement - boosting August results and helping West Coast ports regain some market share, he said.

While some shipping analysts expect the drought in Panama to shift some cargo to the West Coast, the Los Angeles port is not yet receiving shipments from customers who usually route goods bound for the East and Gulf Coasts through that shortcut, Seroka said.

Meanwhile, retailer shipments for holidays including Halloween and Christmas are expected to be "muted" as China exports remain weak and excess inventories continue to weigh on demand, he said.

(Reporting by Lisa Baertlein in Los Angeles; Editing by Sandra Maler)